This invention relates to a process for coloring polymer resins with a reactive, poly(oxyalkylene) substituted disazo colorant, and in particular to a disazo colorant, which is incorporated into the backbone of a polyurethane resin.
The use of poly(oxyalkylene) substituted colorants in thermosetting resins is well known and may be found in the following references: Cross et al., U.S. Pat. No. 4,284,729; Kluger et al., U.S. Pat. No. 4,507,407; Kluger et al., U.S. Pat. No. 4,751,254; Kluger et al., U.S. Pat. No. 4,761,502; Kluger et al., U.S. Pat. No. 4,775,748; Rekers et al., U.S. Pat. No. 4,846,846; Kluger et al., U.S. Pat. No. 4,912,203 and Machell et al., U.S. Pat. No. 5,231,135.
In a subsequent development, the reactivity of the colorants was enhanced by providing branched poly(oxyalkylene) chains, each with multiple reactive terminal groups. The branching was promoted by incorporating glycidol or chloropropane diol in the poly(oxyalkylene) substituent. Examples of the branched reactive colorants may be found in the following references: Kluger et al., U.S. Pat. No. 5,082,938 and Moody et al., U.S. Pat. No. 5,290,921. While the aforementioned colorants have greater reactivity and thus lower extractability, there are drawbacks associated with their use. Glycidol is a relatively expensive raw material and its use significantly increases the cost of the product. Additionally, in some applications, it is desirable to limit the viscosity of the colorant and the branched poly(oxyalkylene) chains tend to increase the viscosity.
Typically, a product line of reactive colorants for polymer resins will include three to five "primary" colorants, which may be blended to match virtually any desired shade. One prior art primary colorant is a poly(oxyalkylene) substituted, orange monoazo colorant. While the orange colorant provided good color space and shade stability, the intermediates used in synthesis are costly and not readily available.
Poly(oxyalkylene) substituted bisazo colorants have been disclosed for use as fugitive tints in Hines et al., U.S. Pat. No. 5,108,460 and Hauser et al., U.S. Pat. No. 4,113,721. The poly(oxyalkylene) substituent provides water solubility to the colorant. Fugitive tints may be used to temporarily color yarns during textile manufacture as a way to identify fibers and grades, and also to facilitate the repair of broken yarns. The fugitive tint is later washed from the textile prior to dyeing and finishing.